EP2119915B1 - Two-stage screw compressor and refrigerating device - Google Patents
Two-stage screw compressor and refrigerating device Download PDFInfo
- Publication number
- EP2119915B1 EP2119915B1 EP09154907.1A EP09154907A EP2119915B1 EP 2119915 B1 EP2119915 B1 EP 2119915B1 EP 09154907 A EP09154907 A EP 09154907A EP 2119915 B1 EP2119915 B1 EP 2119915B1
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- EP
- European Patent Office
- Prior art keywords
- stage
- motor
- compressor
- flow passage
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/008—Hermetic pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
- F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/0042—Driving elements, brakes, couplings, transmissions specially adapted for pumps
- F04C29/005—Means for transmitting movement from the prime mover to driven parts of the pump, e.g. clutches, couplings, transmissions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/04—Heating; Cooling; Heat insulation
- F04C29/045—Heating; Cooling; Heat insulation of the electric motor in hermetic pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/04—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type
- F25B1/047—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type of screw type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B31/00—Compressor arrangements
- F25B31/006—Cooling of compressor or motor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
Definitions
- the present invention relates to a two-stage screw compressor and a refrigerating device.
- Japanese Laid-Open Patent Publication (Kokai) JP 2007-40294 A discloses a two-stage screw compressor which includes a box body forming a flow passage connecting an outlet of a first-stage compressor and an inlet of a second-stage compressor, and the box body stores gears which drive rotor shafts of the first-stage and second-stage compressors.
- a drive shaft which drives the gears driving the rotor shafts of the first-stage and second-stage compressors passes through the box body, and a mechanical seal is provided at a pass-through portion of the drive shaft to seal a compressed fluid.
- GB 1 361 604 A discloses a two-stage screw compressor being similar as in the preamble of the new claim 1.
- WO 2007/026047 A1 discloses a cooling system for an aggregate set, in which the aggregate set comprises an electric machine with a disc-like rotor and a disc-like stator, and a screw compressor.
- the electric machine comprises a cylindrical and airtight sealed housing, which is limited from the sides by end casings and from the periphery by a peripheral casing.
- the two-stage screw compressor of claim 1 can seal a rotor shaft of the first-stage compressor, a rotor shaft of the second-stage compressor, and a shaft of the motor in a casing of the first-stage compressor, a casing of the second-stage compressor, the box body, and the casing of the motor, and it is thus not necessary to seal the rotating shafts from the outside. Therefore, the fluid to be compressed will not leak to the outside. Moreover, it is possible to eliminate a difference in pressure between the internal space of the motor and the connection space, and the fluid will thus not blow through a bearing of the motor, so grease will not flow out. Further, it is also possible to cause the fluid to be compressed to cool an interior of the motor.
- the casing of the motor may include a motor flow passage for introducing the fluid into the internal space of the casing.
- This configuration can more surely cool the motor by introducing the fluid at a low temperature into the motor.
- the two-stage screw compressor according to the present invention may further include a jacket provided outside the casing of the motor.
- This configuration can cool the motor using a refrigerant other than the fluid to be compressed.
- the fluid for cooling the motor will not directly contact with a stator and a rotor, will not thus excessively cool the motor, and will not induce vibration of the rotor caused by injection of the fluid.
- the jacket may include a flow passage which can introduce the fluid from the outside, and an internal space of the jacket may communicate with the connection space. Further, the jacket may include a flow passage which can introduce a fluid from the outside, and a flow passage which discharges the fluid introduced from the outside to the outside.
- a refrigerating device includes the above-described two-stage screw compressor, a condenser, an expansion valve, an evaporator, and a circulation flow passage in which the two-stage screw compressor, the condenser, the expansion valve, and the evaporator are disposed.
- the casing of the motor may include a motor flow passage for introducing the fluid into the internal space of the casing in the two-stage screw compressor, and the refrigerating device may further includes a cooling flow passage that introduces a part of a fluid being downstream side from the condenser to the motor flow passage.
- This configuration does not leak the refrigerant to the outside, cools the motor, and can thus maintain a proper operation state.
- connection space simultaneously serving as the flow passage connecting the outlet of the first-stage compressor and the inlet of the second-stage compressor with each other, and serving as the space storing the transmission mechanism for connecting the shafts of the first-stage compressor and the second-stage compressor with the shaft of the motor with each other, can form the sealed structure in the two-stage screw compressor.
- the sealed structure all the shafts of the first-stage compressor, the second-stage compressor, and the motor, are not exposed.
- the present invention provides the two-stage screw compressor without the leakage of the fluid to be compressed due to difficulty of sealing shafts completely.
- FIG. 1 is a cross-sectional view of a two-stage screw compressor 1 according to a first embodiment of the present invention.
- the two-stage screw compressor 1 includes a first-stage compressor 2 which compresses a fluid, a second-stage compressor 3 which further compresses the fluid compressed by the first-stage compressor 2, and a motor 4 which drives the first-stage compressor 2 and the second-stage compressor 3.
- the first-stage compressor 2 stores a screw rotor 8 in a rotor chamber 6 formed in a common casing 5 shared by the first-stage compressor 2 and the second-stage compressor 3, and the screw rotor 8 includes a rotor shaft 7 and can rotate.
- An inlet flow passage 9 which can be connected via a flange to a pipe line for sucking a fluid into the rotor chamber 6 is formed on the common casing 5.
- an outlet flow passage 10 which discharges the fluid from the rotor chamber 6 is widely opened.
- a pinion gear 11 used to drive the rotor shaft 7 to rotate is provided on an end on an outlet side of the rotor shaft 7.
- the second-stage compressor 3 stores a screw rotor 14 including a rotor shaft 13 in a rotor chamber 12 formed in the common casing 5, and the direction of compressing the fluid by the screw rotor 14 is opposite to that of the screw rotor 8 of the first-stage compressor 2.
- An outlet flow passage 15 of the second-stage compressor 3 is formed on the common casing 5, and the outlet flow passage 15 can be connected via a flange to discharge the compressed fluid from the rotor chamber 12.
- an inlet flow passage 16 of the second-stage compressor 3 for sucking the fluid into the rotor chamber 12 is opened on the same side as the outlet flow passage 10 of the first-stage compressor 2.
- a pinion gear 17 used to drive the rotor shaft 13 to rotate is provided on an end on an inlet side of the rotor shaft 13 like the end of the outlet side of the rotor shaft 7 of the first-stage compressor 2.
- Caps 18 and 19 seal the common casing 5 at an end of the inlet side of the first-stage compressor 2 and at an end of the outlet side of the second-stage compressor 3 respectively. Moreover, an end on the outlet side of the first-stage compressor 2, and an end on the inlet side of the second-stage compressor 3 are integrated with each other, therefore, the common casing 5 is largely opened.
- the motor 4 stores a stator 21 and a rotor 22 in a casing 20, and is sealed by an end surface plate 23. Moreover, in the motor 4, a shaft 24 of the rotor 22 protrudes through the end surface plate 23, and the shaft 24 is supported to rotate by a bearing 25 held by the end surface plate 23. Further, a pull gear 26 is mounted on the shaft 24 of the motor 4, and the pull gear 26 meshes with the pinion gear 11 of the first-stage compressor 2 and the pinion gear 17 of the second-stage compressor 3 to drive the rotor shafts 7 and 13 to rotate.
- the two-stage screw compressor 1 further includes a box body 28 which is connected to an open end of the common casing 5 to form a connection space 27 which servers as a flow passage which connects the outlet flow passage 10 of the first-stage compressor 2 and the inlet flow passage 16 of the second-stage compressor 3 with each other.
- the connection space 27 stores the pinion gear 11 of the first-stage compressor 2, the pinion gear 17 of the second-stage compressor 3, and the pull gear 26 of the motor 3, namely, a transmission mechanism for transmitting a rotation force from the motor 4 to the first-stage compressor 2 and the second-stage compressor 3.
- An opening 29 through which the pull gear 26 can be inserted is provided on the box body 28, and this opening 29 is sealed by the casing 20 of the motor 4.
- connection holes 30 which communicate an internal space of the motor 4 with the connection space 27 are provided on the end surface plate 23 of the motor 4.
- a motor flow passage 31 in a nozzle shape is provided on the casing 20 of the motor 4 to introduce the same fluid that is compressed by the two-stage screw compressor 1 into an internal space of the casing 20.
- any of the rotating shafts are not exposed to the outside. Therefore, dynamic seals are not necessary for sealing the fluid to be compressed within the compressor, and only static seals such as packings and gaskets can surely prevent the fluid from leaking.
- connection holes 30 prevents an operation state of the two-stage screw compressor 1 from generating a difference in pressure between the connection space 27 and the internal space of the motor 4, therefore, the fluid is not blown through the inside of the bearing 25, so grease and lubricant in the bearing 25 is not washed out, and the bearing 25 is consequently not worn soon. Further, heat generated inside the motor 4 is taken by the fluid flowing into the internal space of the motor 4, and is then released to the outside from the second-stage compressor 3, so the motor 4 is prevented from being overheated. Moreover, the motor 4 is more efficiently prevented from being overheated by introducing a fluid at a low temperature from the motor flow passage 31 if necessary.
- FIG. 2 shows a refrigerating device 41 employing the two-stage screw compressor 1 according to the first embodiment.
- the refrigerating device 41 includes a circulation flow passage 46 in which the two-stage screw compressor 1, an oil separator 42, a condenser 43, an expansion valve 44, and an evaporator 45 are disposed, the circulation flow passage 46 circulating a refrigerant, and further includes a cooling flow passage 48 which introduces a part of the refrigerant from the downstream side of the circulation flow passage 46 with respect to the condenser 43, to the motor flow passage 31 of the two-stage screw compressor 1 via an expansion valve 47.
- the refrigerant will not leak, and the motor of the two-stage screw compressor 1 is cooled to perform an efficient operation. Moreover, the refrigerant introduced from the motor flow passage 31 cools the motor 4, then passes through the connection holes 30, and is sucked into the inlet flow passage 16 of the second-stage compressor 3.
- the refrigerant heated to a certain level after cooling the motor 4 is not sucked from the inlet flow passage 9 of the first-stage compressor 2, but from the inlet flow passage 16 of the second-stage compressor 3, the fluid (refrigerant) sucked from the inlet flow passage 9 of the first-stage compressor 2 is not heated, and the decrease of the weight flow rate is thus prevented.
- a sufficient quantity of the refrigerant can pass through the evaporator 45, and the refrigerating device 41 thus can exert a sufficient refrigerating performance.
- FIG. 3 shows a two-stage screw compressor 1a according to a second embodiment of the present invention.
- the motor 4 includes a jacket 51, the jacket 51 being provided with a motor flow passage 52 for introducing the fluid to be compressed, and the casing 20 is provided with a communication hole 53 for communicating the jacket 51 and the connection space 27 with each other.
- the stator 21 and the rotor 22 of the motor 4 are indirectly cooled, and the motor 4 is thus not overcooled.
- the fluid to be compressed such as a refrigerant does not leak out also from the two-stage screw compressor 1a according to the present embodiment.
- the fluid is not directly injected on the rotor 22 or the like of the motor 4, vibration of the motor 4 caused by injection of the fluid will not be induced.
- FIG. 4 shows a two-stage screw compressor 1b according to a third embodiment of the present invention.
- the communication hole 53 is not provided, and the jacket 51 is isolated from the connection space 27.
- the jacket 51 is includes a flow-out flow passage 54 which serves as a flow outlet of a fluid introduced from the motor flow passage 52.
- a fluid different from the fluid to be compressed by the two-stage screw compressor 1b can be introduced into the jacket 51, and is caused to cool the motor 4.
- the fluid to be compressed by the two-stage screw compressor 1b may be introduced into the jacket 51, and the fluid flowing out the flow-out flow passage 54 may be fed to the inlet flow passage 9 of the two-stage screw compressor 1b.
- the box body 28 for forming the connection space 27 may be formed integrally with the casing 5 of the first-stage compressor 2 and/or the second-stage compressor 3.
Description
- The present invention relates to a two-stage screw compressor and a refrigerating device.
- Japanese Laid-Open Patent Publication (Kokai)
JP 2007-40294 A - However, it is not easy to completely seal a rotating shaft, and, when a toxic refrigerant such as ammonia is to be compressed, the refrigerant cannot completely be sealed only with this mechanical seal, and there is a problem that the refrigerant leaks.
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GB 1 361 604 A -
WO 2007/026047 A1 discloses a cooling system for an aggregate set, in which the aggregate set comprises an electric machine with a disc-like rotor and a disc-like stator, and a screw compressor. The electric machine comprises a cylindrical and airtight sealed housing, which is limited from the sides by end casings and from the periphery by a peripheral casing. - In view of the foregoing problems, it is an object of the present invention to provide a two-stage screw compressor which can completely prevent leakage of a fluid to be compressed and a refrigerating device without leakage of a refrigerant.
- With respect to the two-stage screw compressor, the above object is solved by a two-stage screw compressor having the features of claim 1. A refrigerating device is stated in claim 6. Further developments are stated in the dependent claims.
- The two-stage screw compressor of claim 1 can seal a rotor shaft of the first-stage compressor, a rotor shaft of the second-stage compressor, and a shaft of the motor in a casing of the first-stage compressor, a casing of the second-stage compressor, the box body, and the casing of the motor, and it is thus not necessary to seal the rotating shafts from the outside. Therefore, the fluid to be compressed will not leak to the outside. Moreover, it is possible to eliminate a difference in pressure between the internal space of the motor and the connection space, and the fluid will thus not blow through a bearing of the motor, so grease will not flow out. Further, it is also possible to cause the fluid to be compressed to cool an interior of the motor.
- Moreover, in the two-stage screw compressor according to the present invention, the casing of the motor may include a motor flow passage for introducing the fluid into the internal space of the casing.
- This configuration can more surely cool the motor by introducing the fluid at a low temperature into the motor.
- Moreover, the two-stage screw compressor according to the present invention may further include a jacket provided outside the casing of the motor.
- This configuration can cool the motor using a refrigerant other than the fluid to be compressed. In addition, the fluid for cooling the motor will not directly contact with a stator and a rotor, will not thus excessively cool the motor, and will not induce vibration of the rotor caused by injection of the fluid.
- Moreover, in the two-stage screw compressor according to the present invention, the jacket may include a flow passage which can introduce the fluid from the outside, and an internal space of the jacket may communicate with the connection space. Further, the jacket may include a flow passage which can introduce a fluid from the outside, and a flow passage which discharges the fluid introduced from the outside to the outside.
- A refrigerating device according to the present invention includes the above-described two-stage screw compressor, a condenser, an expansion valve, an evaporator, and a circulation flow passage in which the two-stage screw compressor, the condenser, the expansion valve, and the evaporator are disposed.
- With this configuration, in the refrigerating device, rotating shafts will not protrude to the outside, and it is thus not necessary to seal the rotating shafts from the outside. Therefore, a refrigerant will not leak to the outside.
- Moreover, in the refrigerating device according to the present invention, the casing of the motor may include a motor flow passage for introducing the fluid into the internal space of the casing in the two-stage screw compressor, and the refrigerating device may further includes a cooling flow passage that introduces a part of a fluid being downstream side from the condenser to the motor flow passage.
- This configuration does not leak the refrigerant to the outside, cools the motor, and can thus maintain a proper operation state.
- According to the present invention, providing the connection space simultaneously serving as the flow passage connecting the outlet of the first-stage compressor and the inlet of the second-stage compressor with each other, and serving as the space storing the transmission mechanism for connecting the shafts of the first-stage compressor and the second-stage compressor with the shaft of the motor with each other, can form the sealed structure in the two-stage screw compressor. In the sealed structure, all the shafts of the first-stage compressor, the second-stage compressor, and the motor, are not exposed. As a result, the present invention provides the two-stage screw compressor without the leakage of the fluid to be compressed due to difficulty of sealing shafts completely.
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FIG. 1 is a cross-sectional view of a two-stage screw compressor according to a first embodiment of the present invention; -
FIG. 2 is a schematic diagram of a refrigerating device including the two-stage screw compressor shown inFIG. 1 ; -
FIG. 3 is a cross-sectional view of a two-stage screw compressor according to a second embodiment of the present invention; and -
FIG. 4 is a cross-sectional view of a two-stage screw compressor according to a third embodiment of the present invention. - A description will now be given to embodiments of the present invention with reference to drawings.
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FIG. 1 is a cross-sectional view of a two-stage screw compressor 1 according to a first embodiment of the present invention. The two-stage screw compressor 1 includes a first-stage compressor 2 which compresses a fluid, a second-stage compressor 3 which further compresses the fluid compressed by the first-stage compressor 2, and a motor 4 which drives the first-stage compressor 2 and the second-stage compressor 3. - The first-stage compressor 2 stores a
screw rotor 8 in a rotor chamber 6 formed in acommon casing 5 shared by the first-stage compressor 2 and the second-stage compressor 3, and thescrew rotor 8 includes arotor shaft 7 and can rotate. An inlet flow passage 9 which can be connected via a flange to a pipe line for sucking a fluid into the rotor chamber 6 is formed on thecommon casing 5. On the other hand, anoutlet flow passage 10 which discharges the fluid from the rotor chamber 6 is widely opened. Moreover, apinion gear 11 used to drive therotor shaft 7 to rotate is provided on an end on an outlet side of therotor shaft 7. - The second-
stage compressor 3 stores ascrew rotor 14 including arotor shaft 13 in arotor chamber 12 formed in thecommon casing 5, and the direction of compressing the fluid by thescrew rotor 14 is opposite to that of thescrew rotor 8 of the first-stage compressor 2. Anoutlet flow passage 15 of the second-stage compressor 3 is formed on thecommon casing 5, and theoutlet flow passage 15 can be connected via a flange to discharge the compressed fluid from therotor chamber 12. And aninlet flow passage 16 of the second-stage compressor 3 for sucking the fluid into therotor chamber 12 is opened on the same side as theoutlet flow passage 10 of the first-stage compressor 2. Moreover, apinion gear 17 used to drive therotor shaft 13 to rotate is provided on an end on an inlet side of therotor shaft 13 like the end of the outlet side of therotor shaft 7 of the first-stage compressor 2. -
Caps common casing 5 at an end of the inlet side of the first-stage compressor 2 and at an end of the outlet side of the second-stage compressor 3 respectively. Moreover, an end on the outlet side of the first-stage compressor 2, and an end on the inlet side of the second-stage compressor 3 are integrated with each other, therefore, thecommon casing 5 is largely opened. - The motor 4 stores a
stator 21 and arotor 22 in acasing 20, and is sealed by anend surface plate 23. Moreover, in the motor 4, ashaft 24 of therotor 22 protrudes through theend surface plate 23, and theshaft 24 is supported to rotate by abearing 25 held by theend surface plate 23. Further, apull gear 26 is mounted on theshaft 24 of the motor 4, and thepull gear 26 meshes with thepinion gear 11 of the first-stage compressor 2 and thepinion gear 17 of the second-stage compressor 3 to drive therotor shafts - The two-stage screw compressor 1 further includes a
box body 28 which is connected to an open end of thecommon casing 5 to form aconnection space 27 which servers as a flow passage which connects theoutlet flow passage 10 of the first-stage compressor 2 and theinlet flow passage 16 of the second-stage compressor 3 with each other. Theconnection space 27 stores thepinion gear 11 of the first-stage compressor 2, thepinion gear 17 of the second-stage compressor 3, and thepull gear 26 of themotor 3, namely, a transmission mechanism for transmitting a rotation force from the motor 4 to the first-stage compressor 2 and the second-stage compressor 3. - An
opening 29 through which thepull gear 26 can be inserted is provided on thebox body 28, and this opening 29 is sealed by thecasing 20 of the motor 4. Moreover,connection holes 30 which communicate an internal space of the motor 4 with theconnection space 27 are provided on theend surface plate 23 of the motor 4. Moreover, amotor flow passage 31 in a nozzle shape is provided on thecasing 20 of the motor 4 to introduce the same fluid that is compressed by the two-stage screw compressor 1 into an internal space of thecasing 20. - In the two-stage screw compressor 1, any of the rotating shafts are not exposed to the outside. Therefore, dynamic seals are not necessary for sealing the fluid to be compressed within the compressor, and only static seals such as packings and gaskets can surely prevent the fluid from leaking.
- Moreover, the provision of the
connection holes 30 prevents an operation state of the two-stage screw compressor 1 from generating a difference in pressure between theconnection space 27 and the internal space of the motor 4, therefore, the fluid is not blown through the inside of thebearing 25, so grease and lubricant in thebearing 25 is not washed out, and thebearing 25 is consequently not worn soon. Further, heat generated inside the motor 4 is taken by the fluid flowing into the internal space of the motor 4, and is then released to the outside from the second-stage compressor 3, so the motor 4 is prevented from being overheated. Moreover, the motor 4 is more efficiently prevented from being overheated by introducing a fluid at a low temperature from themotor flow passage 31 if necessary. -
FIG. 2 shows a refrigeratingdevice 41 employing the two-stage screw compressor 1 according to the first embodiment. The refrigeratingdevice 41 includes acirculation flow passage 46 in which the two-stage screw compressor 1, anoil separator 42, acondenser 43, anexpansion valve 44, and anevaporator 45 are disposed, thecirculation flow passage 46 circulating a refrigerant, and further includes acooling flow passage 48 which introduces a part of the refrigerant from the downstream side of thecirculation flow passage 46 with respect to thecondenser 43, to themotor flow passage 31 of the two-stage screw compressor 1 via anexpansion valve 47. - According to the present embodiment, the refrigerant will not leak, and the motor of the two-stage screw compressor 1 is cooled to perform an efficient operation. Moreover, the refrigerant introduced from the
motor flow passage 31 cools the motor 4, then passes through the connection holes 30, and is sucked into theinlet flow passage 16 of the second-stage compressor 3. In other words, in case of a two-stage screw compressor in which two stages of compressors, namely the first-stage compressor 2 and the second-stage compressor 3, are serially arranged as in the present embodiment, it is important to prevent the fluid (refrigerant) sucked from the inlet flow passage 9 of the first-stage compressor 2 from being heated for preventing the weight flow rate of the sucked fluid (refrigerant) from decreasing. According to the present embodiment, since the refrigerant heated to a certain level after cooling the motor 4, is not sucked from the inlet flow passage 9 of the first-stage compressor 2, but from theinlet flow passage 16 of the second-stage compressor 3, the fluid (refrigerant) sucked from the inlet flow passage 9 of the first-stage compressor 2 is not heated, and the decrease of the weight flow rate is thus prevented. Thus, a sufficient quantity of the refrigerant can pass through theevaporator 45, and the refrigeratingdevice 41 thus can exert a sufficient refrigerating performance. -
FIG. 3 shows a two-stage screw compressor 1a according to a second embodiment of the present invention. In the following description, same components as the first embodiment are denoted by same numerals, and repeated explanation therefor will be omitted. According to the present embodiment, the motor 4 includes ajacket 51, thejacket 51 being provided with amotor flow passage 52 for introducing the fluid to be compressed, and thecasing 20 is provided with acommunication hole 53 for communicating thejacket 51 and theconnection space 27 with each other. - According to the present embodiment, the
stator 21 and therotor 22 of the motor 4 are indirectly cooled, and the motor 4 is thus not overcooled. Moreover, the fluid to be compressed such as a refrigerant does not leak out also from the two-stage screw compressor 1a according to the present embodiment. Moreover, since the fluid is not directly injected on therotor 22 or the like of the motor 4, vibration of the motor 4 caused by injection of the fluid will not be induced. - Further,
FIG. 4 shows a two-stage screw compressor 1b according to a third embodiment of the present invention. According to the present embodiment, thecommunication hole 53 is not provided, and thejacket 51 is isolated from theconnection space 27. Then, thejacket 51 is includes a flow-outflow passage 54 which serves as a flow outlet of a fluid introduced from themotor flow passage 52. - According to the present embodiment, a fluid different from the fluid to be compressed by the two-
stage screw compressor 1b can be introduced into thejacket 51, and is caused to cool the motor 4. Of course, the fluid to be compressed by the two-stage screw compressor 1b may be introduced into thejacket 51, and the fluid flowing out the flow-outflow passage 54 may be fed to the inlet flow passage 9 of the two-stage screw compressor 1b. - Moreover, according to the present invention, the
box body 28 for forming theconnection space 27 may be formed integrally with thecasing 5 of the first-stage compressor 2 and/or the second-stage compressor 3.
Claims (7)
- A two-stage screw compressor (1), comprising
a first-stage compressor (2) that compresses a fluid;
a second-stage compressor (3) that further compresses the fluid compressed by said first-stage compressor (2);
a motor (4) that drives said first-stage compressor (2) and said second-stage compressor (3), and is stored in a casing (20); and
a box body (28) that serves as a flow passage connecting an outlet (10) of said first-stage compressor (2) and an inlet (16) of said second-stage compressor (3), and also forms a connection space (27) storing a transmission mechanism for transmitting a rotation force from said motor (4) to said first-stage compressor (2) and to said second-stage compressor (3),
characterized in that
said connection space (27) is sealed by an end surface plate (23) of said casing (20) of said motor (4), said end surface plate (23) having a connection hole (30) which communicates said connection space (27) and an internal space of said casing (20) of said motor (4) with each other. - The two-stage screw compressor (1) according to claim 1, wherein said casing (20) of said motor (4) comprises a motor flow passage (31) for introducing the fluid into said internal space of said casing (20).
- The two-stage screw compressor (1) according to claim 1, further comprising a jacket (51) provided outside said casing (20) of said motor (4).
- The two-stage screw compressor (1) according to claim 3, wherein said jacket (51) comprises a flow passage (52) which can introduce the fluid from the outside, and an internal space of said jacket (51) communicates with said connection space (27).
- The two-stage screw compressor (1) according to claim 3, wherein said jacket (51) comprises a flow passage (52) which can introduce a fluid from the outside, and a flow passage (54) which discharges the fluid introduced from the outside to the outside.
- A refrigerating device (41) comprising:said two-stage screw compressor (1) according to claim 1;a condenser (43);an expansion valve (44);an evaporator (45); anda circulation flow passage (46) in which said two-stage screw compressor (1), said condenser (43), said expansion valve (44), and said evaporator (45) are disposed.
- The refrigerating device (41) according to claim 6, wherein said casing (20) of said motor (4) comprises a motor flow passage (31) for introducing the fluid into said internal space of said casing (20) in said two-stage screw compressor (1), the refrigerating device further comprises a cooling flow passage (48) that introduces a part of a fluid being downstream side from said condenser (43) to said motor flow passage.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008124680A JP5197141B2 (en) | 2008-05-12 | 2008-05-12 | Two-stage screw compressor and refrigeration system |
Publications (3)
Publication Number | Publication Date |
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EP2119915A2 EP2119915A2 (en) | 2009-11-18 |
EP2119915A3 EP2119915A3 (en) | 2014-04-30 |
EP2119915B1 true EP2119915B1 (en) | 2016-11-30 |
Family
ID=40874631
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Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP09154907.1A Expired - Fee Related EP2119915B1 (en) | 2008-05-12 | 2009-03-11 | Two-stage screw compressor and refrigerating device |
Country Status (5)
Country | Link |
---|---|
US (1) | US8205469B2 (en) |
EP (1) | EP2119915B1 (en) |
JP (1) | JP5197141B2 (en) |
KR (1) | KR101143166B1 (en) |
CN (1) | CN101581304B (en) |
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Also Published As
Publication number | Publication date |
---|---|
CN101581304A (en) | 2009-11-18 |
JP5197141B2 (en) | 2013-05-15 |
CN101581304B (en) | 2014-06-25 |
JP2009275517A (en) | 2009-11-26 |
US20090277215A1 (en) | 2009-11-12 |
EP2119915A3 (en) | 2014-04-30 |
EP2119915A2 (en) | 2009-11-18 |
US8205469B2 (en) | 2012-06-26 |
KR20090117988A (en) | 2009-11-17 |
KR101143166B1 (en) | 2012-05-11 |
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